So, I've been wanting to learn how to use hydraulics and more specifically, hydraulic motors.
When I look this stuff up in the interweb, all I come up with are very technical charts and such....as well as the google shopping list.

What I'd like to do is find a motor and pump that can propel a vehicle 1500 lbs max (including persons) at a speed of about 10 mph.

I've worked with hydraulics, but only installing them in machinery, using blueprints. So, while knowing how to fit everything together and a basic knowledge of how hydraulics work.......I'm a layman and the engineering terms and language makes me cringe.

Does anyone out there know how to match up a motor and pump that can explain in terms of a complete idiot? OK....not a complete idiot.
I'm just confused and don't want to waste money on the wrong parts.
I'm a steel fabricator and plan on building the fluid tank myself....unless the tank is pressurized. As far as I know, the tank for hydraulics is just a holding tank. Am I right? There's no pressure in the tank?

Perhaps you could repurpose a hydrostatic drive system for a ride on lawnmower. All the components would be there and some what matched up. Gearing for reasonable driving on the playa might be accomplished by larger wheel and tire size.

This eliminates the up side of the satisfaction of developing your own power transfer system but perhaps there would be enough modification to make it worth while. Making a larger than stock custom tank would be a great way to add more capacity for fluid and keep the fluid cooler for better operation on the hot playa.

I think the hydraulic circuit is this... Tank--filter--pump--adjustable high pressure bypass with return to tank--control valving--motor--return to tank.
Depending on the type of control valving the bypass may not be needed if the control contains a bypass that returns pressurized fluid back to the tank when it is in a position where it is not sending power to the motor.

The portion between the pump and pressure side of the motor is the only portion under high pressure. Supply lines to the pump and return to tank from motor are usually oversized to prevent power loss through friction loss. From what I recall the oversize is roughly double what the pressure size hose diameter is. Filters are commonly mounted directly to the tank with NPT pipe and fittings. Definitely avoid a scenario where the filter is pressurized.

Ok. Now that is the basic limit of my knowledge.

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second step, what is the final drive ratio/ gearing. Are the wheels to be mounted to the motor directly, or some gearing/chain drive (highly recommended to minimize torque reqired of the motor. More motor torque requires more pressure or more volume of oil flow, both add to motor cost. chain is cheaper than a big torque motor.

You're right, and to prevent airlocks the tank is mounted higher than filters/pumps. And hey if you're motor's hydraulic, you might as well throw in some rams to do cool things... match open-center or closed-center controls with the correct pump types. Good info: http://en.wikipedia.org/wiki/Hydraulic_machinery, scroll down to hydraulic circuits. happy building! I hate hydraulic oil leaks heheh.

This is about 150 pages of explanations and diagrams of how this stuff really works. Even has hydraulic schematics for garden tractors, log skidders, etc. I used this as a textbook when I used to teach hydraulics at High School Shop many years ago....it sits on my book shelf near the RCA receiving tube manual, transistor manual, and other historical manuals.

One thing about hydraulics, unless you are doing aircraft quality workmanship, there will be oil on the playa.

btw, do not use aircraft fittings unless you do daily dumpster diving at a Aircraft Rework Facility. An aircraft hose end cost many times more than an industrial hose end/fitting. Typically stainless steel and they have a special configuration that only mates aircraft fittings.

I've bought what I would call inexpensive custom made hydraulic lines at an auto parts store. You definitely get what you pay for but I was pleasantly surprised by what I think was a good price and it only took about 10 minutes to have one made up. I had it done at a Big A but I am fairly sure most NAPA stores have the capability.

I think using the components from a zero turn mower would be a great way to go especially since it would be a non standard steering method and = more interesting/odd.

Black Rock City Welding and Repair. The Night Time Warming Station. iGNiTE! Bar.

Card Carrying Member BRCCP.

When you pass the 4th "bridge out!" sign; the flaming death is all yours.-Knowmad-

The link below is to Norton Sales in Los Angeles. They have mountains of hoses, valves and hydraulic aircraft fittings. Saved me tons of money on Crude Awakening, plus it is a really cool place to wander through, but plan on spending time there, (read don't bring SO unless they enjoy that sort of thing)

Whats your budget? Everything you need is in the northern tools catalog.

at a minimum you will need
1. Engine
2. Pump
3. Hydraulic motor
4. Control block (unless one direction is all you want to do)
5. Holding tank - Holding tank is just that, simply hold the Non pressurized oil on return. If it is pressurized it is called a closed loop system, and not necessary.
6. Inline filter, or one attached to the tank. Not as important for a motor, but if you are running cylinders you will chew the cylinder seal up quick. use a filter.
7. hoses - buy off the shelf hoses a little longer than you need. 1/2 the cost of having hoses made.
8. some sort of final drive. if you have some metal working skills you can make up a bracket to hold the motor in place on a car or truck axle. You may need to make up a collar to hold the other half of the u-joint on the hydraulic motor shaft. 90% of hydraulic motors will be made for a keyed shaft, u-joints, as you know are splined. Easy fix with junkyard yoke, chop saw and welding gear or even easier with a lathe. I can help you there as well.

All the parts new from northern would run about 1100.00. 450 of that is for a new gas motor. A lawn mower motor will work - Horizontal shaft is easier to work with. If your in Puget sound area I have an 18Hp Honda gx610 sans exhaust if you want it. came off of a water pump. ran fine then.

Last - use earth friendly hydraulic oil, basically vegetable oil (but not) so dont use veggy oil. it causes way less damage to the environment. Costs twice as much but you will only need 30-50 bucks of it anyways.

Last Last - promise to give me a ride and get me trashed on playa and Ill make up the parts list, assembly instructions and make whatever adapter on my mill or lathe for the yoke and motor for you. I am in an extremely good mood right now.

Here is a super simplified schematic of what you will need. I know all you brainiacs out there you can also plumb from the motor to the reservoir in a flow through motor, but I used a simple single lever block. It depends on what style and size motor you have, some will have a case drain as well that is plumbed back to the reservoir.

Pressured fluid goes to the block from the engine driven pump, you choose which path it goes to the motor - one port goes one way and the other goes the opposite. The fluid has to return somehow to either the reservoir, or in this case the block then to the reservoir. There are more complicated designs out there but you do not need it for one application. You do know that you can add all sorts of cool shit with hydraulics. cylinders to lift, raise close, open things, etc. You also need a filter on the low pressure side, as close to the pump as you can get. this keeps the metal shavings and welding slag you missed from tearing up your pump, then the control block,

If you plan to build one from scratch, research the pump and motors. I used to fix hydraulic equipment for Bobcat. The hoses are not cheap! At least the good ones... You can't jury rig a hydraulic line....and you don't want to dump hydraulic fluid on the playa. Check out a Grainger catalog for detailed info. Just don't buy from them! Way overpriced! Mdmf007's description is spot on. Its a simple set up but if you buy the wrong part, your fucked. $1100 can get you a zero turn mower, already assembled and will save you a lot of homework. Been wanting to build a 1/3 scale Tiger tank for a few years now, using hydraulics as the power source.

mdmf007 wrote:Tom - i have wanted to build a scaled tank for years. cant find the bobcat tracks cheap enough to make it worth it.

I wish I still worked for them. Threw out dozens of used tracks from the shop. I thought the hydraulic part was intimidating...tracks are a nightmare. I'm gonna start shopping around junk yards...the drive sprocket is equally important.

Wow! Thanks everyone!
This all helps me allot. It's all allot to take in, but I keep reading all your posts and I think I've pretty much got it.

mdmf007--That's exactly what I was looking for. A simplified schematic of how it all matches up.

So, here's a few thoughts. I have some very powerful electric motors that I could use to drive the pump. They had plenty of power to drive my last vehicle all over the playa. I'm sure one of them would be enough for the pump.

Another thing....if I remember correctly, aren't most all the hydro fittings and components made of aluminum? If so, I've read that some food processing plants use water as hydro fluid. Since it's liquid it won't compress. No worries of spills on the playa.
If temp is the concern with water, I could rig something up to cool it.
Just a thought. I'm sure there's some reason water isn't used or can't be used, but perhaps there's a way around it?

As far as the zero turn lawnmower goes....I'm not havin it. I like to start things from scratch and treat it as a learning experience. Plus, it's easier for me to buy one part at a time. Gives me more time to come up with the money. Great idea though!

Â¡Niers! wrote:mdmf007--That's exactly what I was looking for. A simplified schematic of how it all matches up.

So, here's a few thoughts. I have some very powerful electric motors that I could use to drive the pump. They had plenty of power to drive my last vehicle all over the playa. I'm sure one of them would be enough for the pump.

Your electric motor will need a power supply, most likely a gas powered engine. Through conservation of energy, going from Gas to produce electricity, to turn an electric motor to turn a hydraulic pump will suck all sorts of efficiency. Your call though

Another thing....if I remember correctly, aren't most all the hydro fittings and components made of aluminum?

You can get hydraulic fittings in steel, and aluminum. Steel is most common.

If so, I've read that some food processing plants use water as hydro fluid. Since it's liquid it won't compress. No worries of spills on the playa.If temp is the concern with water, I could rig something up to cool it.Just a thought. I'm sure there's some reason water isn't used or can't be used, but perhaps there's a way around it?

Water is not used for many reasons, one - it boils at 212. You can get your fluid to 212f in a hydraulic system. The pump, and motor will not have any lubrication if you use water. If you were able to travel a 1/4 mile before you seized your pump, motor or both Id be surprised. Food plants use food friendly hydraulic oil. Veggy based, but not veggy oil. Veggy oil will foam up causing other problems.

Well, I did some reading on water-hydraulics. As I could probably solve the heat problem fairly easy.....the lubrication issue would be a tough one. I've read that there are solutions to this, but then another perhaps more devastating road-block arises.....cost. Water-friendly components are not cheap, possibly doubling my cost.
Not an option.
Now that water is out of the way.
As far as the electric motor goes. I have solar panels and batteries that solves the gas issue. My last vehicle used 2, 24v motors that drove me and 3 others all over the playa as often as we wanted all week long, requiring only one solar charge for the week. I've been a firm believer in "Greening my Burn," so to speak.
I think just one of these motors would be more than enough to run a hydro pump, doubling my battery capacity. If not, I could use both again and have the same efficiency if not better.

So, here's a thought as to reduce the risk of oil spills on the playa.
I could somehow contain all the hoses and components in some sort of container with a tray to catch any leaks.
I guess the best way to combat this problem is to buy quality fittings and keep them clean and tight.
Oil on the playa scares me, so I want to do everything in my power to prevent that.

Â¡Niers! wrote:...As far as the electric motor goes. I have solar panels and batteries that solves the gas issue. My last vehicle used 2, 24v motors that drove me and 3 others all over the playa as often as we wanted all week long, requiring only one solar charge for the week. I've been a firm believer in "Greening my Burn," so to speak.I think just one of these motors would be more than enough to run a hydro pump, doubling my battery capacity. If not, I could use both again and have the same efficiency if not better.

Once again that ugly little gremlin efficiency comes into play. I hate to tell you but compressing fluid to a couple thousand pounds is energy hungry. You would be better off installing the electric motor to the axle through a reduction gear and forego any hydraulics at all.

I hate to be the bearer of bad news - but there is no way you will get any appreciable use from a solar charged, DC Battery, to electric motor, to hydraulic pump, to reduction gear powered ArtCar. You will already be losing at least a third or more of your energy just getting to the hydraulic motor that way, then you have the final drive and tires to factor in. You would need a lot of solar panels to charge the batteries needed, and this thing is not running off of a couple of car batteries mind you. You'll need lots of storage.

First post was wanting to know how to plumb up a hydraulic vehicle. Now you want to run the hydraulics with an electric motor and batteries charged by solar power. You are now creating a Rube Goldberg powered ArtCar, which is cool, but will be completely over engineered and very inefficient.

I suggest you pick one - Hydraulic, or Electric. Either one will be more efficient by itself than both together. It is not a synergistic combination by any means, and is the exact opposite - whatever that would be.

mdmf007 wrote:Once again that ugly little gremlin efficiency comes into play. I hate to tell you but compressing fluid to a couple thousand pounds is energy hungry. You would be better off installing the electric motor to the axle through a reduction gear and forego any hydraulics at all.

I hate to be the bearer of bad news - but there is no way you will get any appreciable use from a solar charged, DC Battery, to electric motor, to hydraulic pump, to reduction gear powered ArtCar. You will already be losing at least a third or more of your energy just getting to the hydraulic motor that way, then you have the final drive and tires to factor in. You would need a lot of solar panels to charge the batteries needed, and this thing is not running off of a couple of car batteries mind you. You'll need lots of storage.

First post was wanting to know how to plumb up a hydraulic vehicle. Now you want to run the hydraulics with an electric motor and batteries charged by solar power. You are now creating a Rube Goldberg powered ArtCar, which is cool, but will be completely over engineered and very inefficient.

I suggest you pick one - Hydraulic, or Electric. Either one will be more efficient by itself than both together. It is not a synergistic combination by any means, and is the exact opposite - whatever that would be.

I guess I haven't given enough thought to how much it would take to run a pump.
I have a decision to make now.
Thanks for all your help, and if I do decide to go with hydro I will let you know. What you said totally makes sense though, and I think you are right, the efficiency factor would most likely make this pointless.
The scale seems to lean towards electric for me now.

I know you want to build your project from scratch, but a zero turn mower can be bought dirt cheap at auction, if you just get it for parts. It will give you an exact idea of how to but it back together, and an idea of how well mounted your motors need to be, to handle the torque.

If I had a bit of extra cash I would use "o- ring face " seals . Easy to use and the biggest benefit is it's not torque sensative. Meaning you can't over tighten them like JIC fittings. Depending on the lenghts of runs, it may also be cheaper to use a combination of tube and hose. Tube being cheaper but you will have more connections.

The Christina huge yacht mutant vehicle is hydraulically driven and steered. It was done with already-matched parts from an old cement mixer truck. It's really really slow though. So slow they flat-tow it rather than drive it onto the playa.

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